Micro-Shear Bond Strength of Indirect Composite Resin to Three Different Computer-Milled Cores After Thermocycling

The aim of this study was to evaluate the micro-shear bond strength of an indirect composite resin to three different types of cores.

In this in-vitro study, 14 blocks (5×5×2 mm) were designed and milled by computer from cobalt-chromium (Co-Cr) alloy, zirconia, and polyether ether ketone (PEEK). Each sample was treated according to the manufacturer’s instructions, and the appropriate primer, and a layer of Crea.lign opaquer were applied on the surface. For micro-shear bond strength test, a plastic tube with an internal diameter of 1 mm and height of 2 mm was placed on each block, and Crea.lign paste was condensed in it. The Crea.lign paste and opaquer were light-cured separately for 180 s, and finally for 360 s. All samples were placed in 37°C distilled water for 24 h and thermocycled for 5000 cycles (5 to 55°C). The microtensile tester machine was used to measure the micro-shear bond strength. The samples were also evaluated for failure modes. Data were analyzed using one-way ANOVA (P<0.05).

According to one-way ANOVA, the mean micro-shear bond strength (MPa) in Co-Cr alloy, zirconia, and PEEK groups was 25.19±5.53, 23.49±5.48, and 20.58±5.68 MPa, respectively. There was no significant difference in micro-shear bond strength of the three groups (P= 0.099). The most frequent mode of failure in all three groups was adhesive, followed by mixed, and cohesive.

Applying the standard procedure, type of core material had no significant effect on the micro-shear bond strength of Crea.lign composite veneer.